Field of the Invention
The present invention relates to an imprint apparatus and an article manufacturing method.
Description of the Related Art
An imprint technique by which an imprint material is placed on a substrate and cured by being irradiated with light while a mold is brought in contact with the imprint material, thereby transferring a pattern of the mold onto the imprint material, is attracting attention. The degree of cure of the imprint material depends on the amount of light with which the imprint material is irradiated. Japanese Patent Laid-Open No. 2012-099197 describes a double-sided imprint apparatus in which the irradiation time of a UV light source arranged in a lower-side stamper is made shorter than that of a UV light source arranged in an upper-side stamper. In this double-sided imprint apparatus, a transferred material can be released from the upper-side stamper after the transferred material is released from the lower-side stamper because the force required for release depends on the irradiation time. “Basis and Practical Use of Photosensitive Resin”, CMC, supervised by Kiyoshi Akamatsu, pp. 242-243 describes that chemical reaction velocity of a radical polymerizable resist is proportional to the square root of illuminance.
In the conventional imprint apparatus, the time during which an imprint material is irradiated with light is optimized in advance, and the imprint material is cured by controlling light irradiation to the imprint material in accordance with the irradiation time. Therefore, if the illuminance decreases due to, for example, deterioration of the light source, cure of the imprint material may become insufficient. In the conventional imprint apparatus, the degree of photopolymerization (the degree of cure) of a radical polymerizable imprint material is not automatically adjusted to a target value.